A microfiche appendix is included in this application showing certain computer software. The appendix comprises one microfiche with 73 frames.
A portion of the disclosure of this patent document contains material which is subject to copyright protection. The copyright owner has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure, as it appears in the Patent and Trademark Office patent file or records, but otherwise reserves all copyright rights whatsoever.
The present invention relates to the production of signs, and in particular, to the printing of an image for a weather resistant sign such as a license plate.
Vehicle license plates are a challenging problem. They must provide an overall similarity of styling or appearance to enable rapid recognition of license plates issued by various licensing authorities and to inhibit counterfeiting. At the same time, license plates need to provide a distinct, individualized, and unique identifier code or image for each vehicle. In essence, each vehicle requires a custom, short run manufacturing process to incorporate its unique code or image upon a commonly styled license plate blank.
The best known manufacturing process for incorporating the unique image has been stamping or embossing a metallic plate to first provide raised letters or numbers on a plate. Subsequently, the raised letters or numbers are contacted by a liquid ink or paint carried upon a roller or pad. The liquid ink or paint dries to provide a contrasting image which corresponds to the embossed image or raised pattern of the plate. In order to improve the weather resistance, after drying of the ink, the plate is dipped in a liquid clear coating agent (i.e. a solvent born resin or plastic). The resulting plate is relatively durable. However, the embossing and inking process is labor intensive. In the U.S. most of the labor for this process has been prison labor. In other areas of the world, however, private industry or governmental employees are the labor sources for license plate manufacture.
In recent years, many licensing authorities have offered xe2x80x9cvanityxe2x80x9d license plates at a premium license fee. Such plates allow the licensee to participate in the selection of an attractive or meaningful printed design to be entered upon their license plates. Unfortunately, the production of such xe2x80x9cvanityxe2x80x9d license plates also entails a significantly greater production cost. Additionally, some licensing authorities desire to reuse previously abandoned identifying codes or images. Preparation of license plates for such nonsequential images also represents a custom manufacturing operation, similar to that required for xe2x80x9cvanityxe2x80x9d plates. A more versatile and efficient printing process would be useful for preparing regular, nonsequential, and vanity license plates.
Another aspect of the present embossing and liquid inking process is the release of solvent vapor from the drying ink. This solvent release is in addition to solvent released by the dipping and subsequent drying of the protective clear coating layer. The manufacture of large quantities of license plates requires substantial investment in drying ovens and solvent vapor ventilation. Increased scrutiny of possible environmental and health risks associated with various solvent vapors appears to be a trend throughout the world. It would be advantageous to eliminate the generation of solvent vapors from the process of printing license plates.
Many traffic signs and license plates have a retroreflective property which is generally considered desirable in the industry. In such cases, inks or paints have been selected for compatibility with the retroreflective materials. A more versatile and efficient printing process would accommodate a variety of colorants and be compatible with retroreflective components used in license plates and traffic signs.
The present invention includes a method of printing a weather resistant sign when provided with a sign component having a surface to be printed and a definition of the image to be printed. Dry toner powder is applied to portions of the surface corresponding to the image definition. The toner is fused to form a fused image upon the surface of the sign component. Preferably the surface, including the fused toner, is covered by a protective coating to seal the fused toner within a weather resistant package. The sign component to be printed may be an opaque or retroreflective sheet or, alternatively, a light transmitting (preferably transparent) cover film for use over an opaque or retroreflective sheet. The image definition may be mechanical, such as by embossing, or digital, such as by a computer generated signal from a stored image, an optically scanned image, an image stored on microfilm or an image composed by a computer operator. The method may be practiced without the generation of solvent vapors and is also suitable for other short runs of signs, such as street name signs.
The present invention also includes a license plate printed by the method of this invention. A license plate of the present invention is a laminate including at least the following layers: a substrate, a retroreflective sheet layer upon the substrate oriented to provide retroreflection of light entering the retroreflective sheet opposite from the side laminated to the substrate, and a discontinuous image layer of fused toner over the retroreflective sheet. A preferred license plate of the present invention is a laminate including at least the following layers: a substrate, a retroreflective sheet layer upon the substrate oriented to provide retroreflection of light entering the retroreflective sheet opposite from the side laminated to the substrate, a transparent protective top layer over the retroreflective sheet layer, and a discontinuous image layer of fused toner sandwiched between the retroreflective sheet layer and the transparent top layer. The license plates optionally may include an embossed image substantially corresponding to the fused toner.